1. Technical Field
The present invention relates to liquid ejection apparatuses, such as an ink jet type recording apparatus, and control methods for a liquid ejection apparatus, and in particular, it relates to a liquid ejection apparatus and a control method for a liquid ejection apparatus which cause liquid to be ejected through a nozzle by, in order to drive a pressure generation means to cause a pressure variation of the liquid which is contained inside a pressure chamber communicated with the nozzle, applying a drive waveform included in a drive signal to the pressure generation means.
2. Related Art
A liquid ejection apparatus is an apparatus which is provided with an ejection head, and ejects (discharges) various kinds of liquid from the ejection head. Well-known examples of this liquid ejection apparatus include an image recording apparatus, such as an ink jet type printer and an ink jet type plotter, and further, nowadays, this liquid ejection apparatus has been applied to various manufacturing apparatuses by exploiting its characteristic that a very small amount of liquid can be landed on a predetermined position with accuracy. For example, the liquid ejection apparatus is applied to a display manufacturing apparatus for manufacturing a color filter for a liquid crystal display or the like, an electrode formation apparatus for forming an electrode for an organic electro-luminescence (EL) display, a face emitting display (FED) or the like, and a chip manufacturing apparatus for manufacturing a biochip (a biochemical chip). Further, a recording head for the image recording apparatus ejects ink in a liquid condition, and a color-material ejection head for the display manufacturing apparatus ejects solution of red (R), green (G) and blue (B) color materials. Further, an electrode-material ejection head for the electrode manufacturing apparatus ejects a liquid electrode material in a liquid condition, and a bio-organic material ejection head for the chip manufacturing apparatus ejects solution of a bio-organic material.
A recording head, which is a kind of the liquid ejection head described above, is provided with a plurality of nozzle rows (nozzle groups) each being configured such that a nozzle for ejecting liquid is arranged in plural rows which are located parallel to one another. Further, this recording head ejects functional liquid through a nozzle by utilizing a pressure variation of the functional liquid inside a pressure chamber, which is caused by a pressure generation means, such as a piezoelectric element, which is driven by a drive waveform applied thereto. In a general liquid ejection head, a voltage (a drive voltage) of the above drive waveform is set to a voltage value which makes an amount (weight or volume) of liquid ejected from each of nozzle rows uniform, and the relevant drive waveform is used in common to the nozzle rows.
JP-A-2007-210234 is an example of related art.
Nevertheless, even in the case where a drive voltage which is set so as to make an amount (weight or volume) of liquid ejected from each of nozzle rows uniform is used, there has sometimes occurred a variation of a flight velocity of liquid ejected through a nozzle among nozzle rows because of a manufacturing variation among pressure generation means, and the like. This variation of the flight velocity also results in a phenomenon in which a landing position of liquid relative to a landing object, such as a recording medium, varies among nozzle rows. Particularly, in these days, there sometimes occurs a case where the liquid ejection apparatus is used in an application which causes liquid to be ejected at a higher drive frequency while causing a liquid ejection head and a landing object to perform a relative movement at a higher speed, and in this case, the variation of the landing position of liquid results in being significant. Moreover, there is a problem that, in a printer in which an ink jet type recording head, which is a kind of liquid ejection head, is mounted, in the case where a configuration in which inks of the same color are ejected through respective nozzles which are included in mutually different nozzle lines is employed, any variation of a landing position of ink between the inks of the same color results in the degradation of an image quality of recorded images or the like.
In an existing configuration, a latch signal LAT and a change signal CH, which are used for control of selection of one of drive pulses included in a drive signal are common to a plurality of nozzle rows, and thus, it has been difficult to adjust ejection timing for each of the nozzle rows. For this reason, unavoidably, it is necessary to suppress the ejection operation speed below a certain speed in view of the above-described variation of a landing position of liquid, and this suppression leads to a decrease of throughput. Meanwhile, there is an alternative configuration which enables a liquid ejection to be performed at timing suitable for a flight velocity of liquid for each of nozzle rows, by providing a drive signal dedicated to each of the nozzle rows, and further providing the latch signal LAT and the change signal CH dedicated to each of the nozzle rows, which are used for control of selection of one of drive pulses included in a drive signal. In order to practice this alternative configuration, however, there has been an obstacle in which the number of signal lines and the complexity of wiring increase, and this leads to the increase of noise generation sources.